from rest_framework import views
from rest_framework.response import Response
from rest_framework.reverse import reverse

from .. import settings


class APIRoot(views.APIView):
    names = ['SITE_NAME', 'SITE_VERBOSE_NAME']
    
    def get(self, request, format=None):
        root_url = reverse('api-root', request=request, format=format)
        token_url = reverse('api-token-auth', request=request, format=format)
        links = [
            '<%s>; rel="%s"' % (root_url, 'api-root'),
            '<%s>; rel="%s"' % (token_url, 'api-get-auth-token'),
        ]
        if not request.user.is_anonymous():
            list_name = '{basename}-list'
            detail_name = '{basename}-detail'
            for prefix, viewset, basename in self.router.registry:
                singleton_pk = getattr(viewset, 'singleton_pk', False)
                if singleton_pk:
                    url_name = detail_name.format(basename=basename)
                    kwargs = { 'pk': singleton_pk(viewset(), request) }
                else:
                    url_name = list_name.format(basename=basename)
                    kwargs = {}
                url = reverse(url_name, request=request, format=format, kwargs=kwargs)
                links.append('<%s>; rel="%s"' % (url, url_name))
            # Add user link
            url_name = detail_name.format(basename='user')
            kwargs = { 'pk': request.user.pk }
            url = reverse(url_name, request=request, format=format, kwargs=kwargs)
            links.append('<%s>; rel="%s"' % (url, url_name))
        headers = { 'Link': ', '.join(links) }
        body = {
            name.lower(): getattr(settings, name, None) for name in self.names
        }
        return Response(body, headers=headers)
    
    def metadata(self, request):
        ret = super(APIRoot, self).metadata(request)
        ret['settings'] = {
            name.lower(): getattr(settings, name, None) for name in self.names
        }
        return ret
